Swimmer&#39;s foot-fin with thrust-accelerating device



(5. BEUCHAT May 18, 1965 SWIMMERS FOOT-FIN WITH THRUST-ACCELERATING DEVICE 2 Sheets-Sheet 1 Filed March 16, 1964 B INVENTOR: gay/e655 BEUCHHT y 18, 1965 G. BEUCHAT 3,183,529

SWIMMERS FOOT-FIN WITH THRUST-ACCELERA'IING DEVICE Filed March 16, 1964 2 Sheets-Sheet 2 Fig.2,

' up, ,I"' 1,111,, I I I I I I b Z NVEA/ 7 0R gfom s 551mm? new H United States Patent 3,183,529 SWIMMERS FOOT-FIN WETH THRUST- ACCELERATIN G DEVICE Georges Beuchat, 129 Rue Jean Mermoz, Marseille, France Filed Mar. 16, 1964, Ser. No. 352,184 4 Claims. (Cl. 9-309) This is a continuation'in-part of my co-pending United States patent application No. 190,084, dated April 25, 1962, now abandoned.

This invention relates to swimmers foot-fins, such as are commonly used for example by swimmers when skindiving or carrying out underwater swimming.

The reason for use of a foot-fin is to obtain a greater propulsive effect than is obtainable with the human foot alone.

Foot fins consist generally of a shoe portion, to receive the swimmers foot, plus a blade portion which forms a forward extension of the foot portion and which has the effect of increasing by several times the area of surface which acts against the water and thus propels the swimmer by reaction.

Although foot fins can be utilized in various different ways and in various different positions of swimming, it is most usual to swim therewith in a position in which the swimmer lies face-downwards in the water, and pro pels himself by alternate kicking movements up and down with the two feet.

Each driving stroke is constituted by an upwards flexing movement of the lower portion of the leg, and after each driving stroke the leg is moved downwards again in a return stroke which has little or no propulsive effect.

It is desirable that the foot-fin, and in particular the blade portion, shall be as effective a water-driving device as possible during the up-stroke (propulsion of the body forward), but shall nevertheless offer the least resistance to forward movement during the down-stroke (coasting of the body forward, or propelled forward by an up-stroke of the other foot).

The object of the present invention is to provide an improved construction of foot fin whereby these and other desirable objects are achieved.

In order that the nature of the invention may be readily ascertained, an embodiment of the foot-fin constructed in accordance therewith is hereinafter particularly described with reference to the accompanying drawing, wherein:

FIG. 1 is a perspective elevation of the foot fin, seen from one side and above.

FIG. 2 is a section on the line 2-2 of FIG. 3.

FIG. 3 is a perspective underplan.

FIGS. 4 and 5 are schematic diagrams to illustrate the manner in which the foot fin operates, FIG. 4 showing an up-stroke (propulsion of the swimmer forwardly) and FIG. 5 showing a downstroke (return stroke).

Referring to FIGS. 1 to 3, the foot-fin comprise a foot portion denoted generally by reference F, and a blade portion denoted generally by reference B. The entire article is made as a one-piece moulding of a resiliently flexible material such as natural rubber or synthetic rubher.

The foot portion F includes two side walls 1 and 2, a heel 3a, a sole 3b, and an upper wall 4. The side walls 1, 2, the heel 3a and the upper wall together define an opening 5 into which the swimmer inserts his foot. The side walls 1, 2, the sole 3b and the upper wall 4 together define an elongated internal chamber to receive and enclose the whole of the swimmers foot forward of the ankle, this chamber terminating forwardly at the position indicated by the ridge 6.

The side walls 1 and 2 are continued forwards as respectively thick intermediate ribs 7 and 8 which reduce in "ice height forwardly until they merge into the general plane of a broad upper blade area 9. Other respective external vertical ribs 10 and 11 diverge forwardly away from the side walls 1 and 2 and likewise reduce in height forwardly and eventually merge into the plane of the upper blade area 9. The blade area 9 forms a web across the four ribs 10, 7, 8, 11, and at its rear edge is joined to said ribs at about half their height.

A central forward continuation 12 of the foot portion passes at a spacing below the rear edge of the blade area 9 and terminates at the position shown in broken line,

thereby defining with the ribs 7 and 8 and the blade 9 a central water-flow channel 13.

The sole is continued forwardly, at each side of the portion 12, as respective side portions 14 and 15 which define with the blade 9 and the associated ribs 7, 10 and 8, 11 a pair of side water-flow channels 16 and 17. All of the channels 13, 16, 17 have, considered in the forward direction, a relatively wider inlet opening and a relatively narrower outlet opening.

Referring now to FIGS. 4 and 5, these show diagrammatically the manner in which water flow occurs during driving and return strokes. In these figures, the foot-fin is assumed to be seen in central vertical longitudinal section.

During a driving stroke the leg 18 as a whole moves upwardly, and the lower limb 19 moves relatively further by pivoting about the knee joint 20. It will be seen from FIG. 4 that during this movement the entire sole area S plus the underside of the central portion 12 (and of the side portions 14, 15), plus the underside of the blade 9 together form a substantially linear paddle which, through being moved approximately vertically in the direction of the arrow 21 (although in fact moving in a motion which is a resultant of two superimposed pivoting movements occurring about the thigh joint and knee joint) and at an angle of, say, 30 to the horizontal, results in a slip of water over the paddle as shown by the arrows 22a, 22b, and a resultant forward reaction thrust which propels the swimmer leftwards in this drawing.

The thrust exerted by the underside of the blade 9 causes local high pressure which propels the adjacent water in the direction of arrow 2212 as three parallel streams in the channels defined by the blade 9 and the ribs. main bulk of water shifted by the fin as a whole, and cause local lowering of pressure in the passages 13, 16, 17, which assists throughdlow of water (see arrow 22c) occurring as a result of the general forward movement of the swimmer.

When the up-stroke has been completed, the leg is kicked downwardly as seen in FIG. 5. The downward movement of the blade portion B against the resistance of the water causes the blade to flex into the generally curved state shown. Bearing in mind that the swimmer is travelling forwardly in a continuous motion, it will be appreciated that:

(a) The blade portion B now lies in a position offering very little resistance to passage (from right to left) through the water, and

(b) The three passages 13, 16, 17 combine to form an escape passage to the rear of the blade portion B for that water which might otherwise tend to pile up at area 23 immediately in front of the toes and blade B, see arrows 24a, 2%, this water being in fact passed through the passages 13, 16, 17 and emerging as relatively accelerated jets which are directed generally along the line of swimming (arrow 24b) and thus exert on the fin a reaction which assists in general forward propulsion of the swimmer (from right to left in this figure). These jets avoid turbulence at area 25 and reduce drag at area 26.

Thus the resistance which would otherwise be presented against forward movement of the swimmer, during the Patented May 18, 1965 These streams move forward more rapidly than the {3 return stroke of each leg, is to a very large extent eliminated.

I claim:

1. A swimmers foot-fin comprising a hollow foot portion open at the heel end to receive the users ankle, and a blade portion extending from the toe end of the foot portion, said blade portion being formed as a Whole of resiliently flexible material, said blade portion including a plurality of transversely-spaced longitudinal ribs, said blade comprising a first lower blade portion forming a forward continuation of the'foot portion and defining with upwardly projecting portions of said ribs a plurality of first longitudinal channels open to the upper side of the fin, and a second staggered upper blade commencing at a point spaced above and intermediate the ends of said channels and extending forwardly to a point forward of said channels, said second blade defining with downwardly projecting portions of said ribs on the lower surface a 4 plurality of second longitudinal channels open to the lower side of the fin.

2. A swimmers foot-fin, as claimed in claim 1, wherein said ribs project upwardly from the upper surface of said second blade, over part of its total length forwardly, to define a plurality of third longitudinal channels open to the upper side of the fin.

3. A swimmers foot-fin,sas claimed in claim 2,wherein said first blade and said second blade both increase in width, considered in the forward direction.

4. A swimmers fo0tfin, as claimed in claim 3, made as a whole as a one-piece moulding of rubber-like material.

References Cited by the Examiner UNITED STATES PATENTS 3,032,787 5/62 Mazzella 9--309 3,055,025 9/62 Ferraro et al 9-309 FERGUS S. MIDDLETON, Primary Examiner, 

1. A SWIMMER''S FOOT-FIN COMPRISING A HOLLOW FOOT PORTION OPEN AT THE HEEL END TO RECEIVE THE USER''S ANKLE, AND A BLADE PORTION EXTENDING FROM THE TOE END OF THE FOOT PORTION, SAID BLADE PORTION BEING FORMED AS A WHOLE OF RESILIENTLY FLEXIBLE MATERIAL, SAID BLADE PORTION INCLUDING A PLURALITY OF TRANSVERSELY-SPACED LONGITUDINAL RIBS, SAID BLADE COMPRISING A FIRST LOWER BLADE PORTION FORMING A FORWARD CONTINUATION OF THE FOOT PORTION AND DEFINING WITH UPWARDLY PROJECTING PORTIONS OF SAID RIBS A PLURALITY OF FIRST LONGITUDINAL CHANNELS OPEN TO THE UPPER SIDE OF THE FIN, AND A SECOND STAGGERED UPPER BLADE COMMENCING AT A POINT SPACED ABOVE AND INTERMEDIATE THE ENDS OF SAID CHANNELS AND EXTENDING FORWARDLY TO A POINT FORWARD OF SAID CHANNELS, SAID SECOND BLADE DEFINING WITH DOWNWARDLY PROJECTING PORTIONS OF SAID RIBS ON THE LOWER SURFACE A PLURALITY OF SECOND LONGITUDINAL CHANNELS OPEN TO THE LOWER SIDE OF THE FIN. 